Curiosity found the organic material in sedimentary rocks – mudstone – after drilling into four areas of the Gale crater, an ancient lake bed in which Curiosity originally landed in 2012.

One of the drill sites in the Gale Crater. Image: NASA/JPL

The samples were heated to 500C in Curiosity’s oven to release any organic molecules, the kind that don’t vaporise easily.

Curiosty’s ‘oven’, otherwise known as SAM. Image: NASA/JPL

NASA’s scientists saw “fragments” of organic molecules that were similar to those found in sedimentary rock on Earth. And they believe the fragments could have been parts of larger molecules present a long, long time ago on Mars.

Maybe even billions of years – the Gale crater, named after Australian astronomer Walter F. Gale, is up to 3.8 billion years old, and may have once held a lake.

Curiosity’s landing zone. Image: NASA/JPL

The presence of sulfur also might explain how the molecules have survived for so long.

And if you’re a scientist searching for signs of life, organic matter hopefully points to, if not a direct indication of life itself, something like life, or something other life forms can live off.

“Are there signs of life on Mars?” said Michael Meyer, lead scientist for NASA’s Mars Exploration Program, at NASA Headquarters. “We don’t know, but these results tell us we are on the right track.”

But the good news didn’t end with that announcement. NASA also announced it had found signs of “seasonal methane” in the Mars atmosphere.

The fluctuations in methane were observed over three Mars years (roughly six Earth years) by Curiosity’s Sample Analysis at Mars (SAM) instruments.

Low levels of methane in Gale crater were shown to repeatedly peak in warm, summer months and drop in the winter every year.

It’s the first time “something repeatable in the methane story” has been observed on Mars, Chris Webster of NASA’s Jet Propulsion Laboratory said.

Again, it doesn’t necessarily point to the presence of biological organisms, as the team admits “water-rock chemistry” could be another source. But they won’t rule out some form of organic growth.

“With these new findings, Mars is telling us to stay the course and keep searching for evidence of life,” said Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA Headquarters.

Gale Crater. Image: NASA/JPL

All of which will be taken into account when several more Mars lander projects head for the Red Planet in the next two years.

The first, NASA’s InSight Lander, will land on November 26 this year and spend two years determine whether the planet is still geologically active.

Curiosity’s upgraded replacement, the Mars 2020 rover, is scheduled to land in early 2021 and start gathering more soil samples.

The European Space Agency’s ExoMars rover will also arrive in 2021 and begin measuring the atmosphere and drilling up to two metres below the surface.